Russia and Eastern Europe have one of the fastest growing HIV epidemics in the world, with transmission risk primarily from injection drug use. Russia and other countries in the region have implemented routine HIV testing within established addiction treatment systems (i.e. narcology hospitals). The narcology system, however, works largely independent of other medical care systems and has not adopted strategies to link HIV- infected patients to HIV care. This is a missed opportunity: up to 45% of Russian injection drug users (IDUs) in narcology treatment have HIV, yet as few as 20% of those infected are in care. To retain those in HIV care the Russian AIDS treatment system has begun using case managers; however these efforts do not consider the unique challenges faced by IDUs that can impact retention nor do they address care initiation. The objective of this study Linking Infectious and Narcology Care (LINC) is to improve upon the treat and retain dimensions of the seek, test, treat, and retain paradigm in Eastern Europe. We will implement and assess a behavioral and structural intervention in Russia designed to support and motivate HIV-infected narcology heroin dependent patients (i.e., IDUs) to engage (i.e., initiate and retain) in HIV medical care and ultimately improve their HIV outcomes. LINC is a clinical model designed to coordinate narcology and HIV systems of care using elements shown to facilitate engagement in medical care: HIV case management and nurse home visits. The central hypothesis is that an intervention that involves coordination between the narcology and HIV systems via a) HIV case management delivered by a peer to help motivate and reduce barriers to HIV care, b) enhanced outpatient narcology treatment by addiction nurses and c) communication between these providers will lead to engagement in HIV care. Implementation research recognizes that effective interventions may not translate successfully across different contexts and systems. Hence, we will assess the organizational and operational issues that drive engagement in HIV care in Russia as well as a comparable setting in another former Soviet Union country, Ukraine. The project will be undertaken by an international research team experienced in addressing HIV, substance use, and clinical interventions in Russia. This proposal's Specific Aims are to assess the effectiveness of the LINC intervention compared to standard of care on 4 distinct outcomes:1) initiation of HIV care (> 1 visit to HIV medical care) within 6 months of enrollment; 2) retention in HIV care (> 1 visit to medical care in 2 consecutive 6 month periods) within 12 months; 3) appropriate HIV care (prescribed ART if CD4 cell count is <350 or having a second CD4 count if CD4 >350 within 12 months; and 4) improved HIV health outcomes (CD4 cell count at 12 months). The final Specific Aim is to establish the contextual factors that influence adoption and sustainability of the LINC intervention in Russia and another Eastern European country. If LINC can embed effectively within Eastern European medical systems, then it has the potential to be widely implemented in this region of the world and have a major impact on the HIV epidemic among IDUs.